Here's what talked me into an X5:

1. www.xoutpost.com
First, the *huge* collection of links and articles on the front page of this place. Amazing resource and educational / diy opportunity.

2. http://www.xoutpost.com/x5-e53-forum/...-used-buy.html
I put a similar thread to you up - should I buy an X5 used? And within twenty minutes I had about five replies. Of course, they all said YES YES YES BUY IT NOW NOW NOW or something similar, but the fact that there are that many people around prepared to pay attention to lil'ol me with a simple question is testament to:
(a) the quality of teh community here
(b) the quality of the X5 that drives that community